Solid State Pulsed Power Systems containing IGBT
switches are mainly operating with input voltages between
400V and 3kV depending on the maximum allowable
blocking voltage of the IGBTs. Nevertheless, high output
voltages of several kilovolt can be achieved for example by
the use of a pulse transformer, a Marx generator
configuration or a combination of both.
The pulse power (e.g. 20MW) is normally provided from a
capacitor bank whereas the average power (here 25kW) is
supplied by a converter [1] connected to the mains, whose
line to line voltage can vary from 177V to 528V world wide.
Depending on the ratio of the mains to the capacitor bank
voltage the converter has to work in a buck or boost mode.
Additionally, due to the possible high repetition rate of pulse
modulators (500-1000Hz) the capacitor bank has to be
recharged before the next pulse is generated, which would
demand a high dynamic voltage control.
In the 3-phase buck boost rectifier [2] a constant current
through the buck boost inductor is needed to provide a unity
power factor. But the pulse load in combination with the high
dynamic voltage control would result in periodic peak
currents at the converter input/mains and therefore a unity
power factor at the input of the converter can not be
guaranteed and the mains current would be distorted.
Therefore, a new control for pulse load applications has to be
implemented which achieves a unity power factor and an
accurate regulation of the output voltage.
First, in the paper the structure/operation principle of a
standard buck boost converter [2] is described and the
problems resulting from the pulse load are discussed.
Thereafter, a new control is derived which avoids the
mentioned problems.
Finally, the paper is concluded with measurement results
for the input currents and the DC voltage during pulse
operation.